Fuels: Ethanol
Argonne National Laboratory's emissions modeling tool, GREET, (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation), calculates the life cycle GHG emissions from ethanol to be 38 percent lower than that of petroleum diesel. For methanol, life cycle emissions are moderately higher. As with biodiesel, the emissions savings for corn-based ethanol results from the assumed re-absorption of CO2 by the growth of the following year's feedstock crop. The lower energy content of ethanol, however, coupled with its high cost, have inhibited widespread adoption of ethanol technology.
The Los Angeles MTA, while citing numerous mechanical difficulties stemming from corrosive nature of ethanol and frequent engine failures, found ethanol's lower on-the- road efficiency the most serious strike against it. "Ethanol was strangling the agency," according to LA's John Drayton. "We were paying more for the fuel and getting less mileage."
After a period of demonstration programs ending in the late 1990's, no transit buses using alcohol fuels such as ethanol or methanol were manufactured in 1999, and there are few indications that alcohol fuels will become the market preference for AFV buses at any time in the near future. Although capital costs are greater for CNG buses, several factors weigh heavily in favor of natural gas and against the alcohol fuels: the lack of a well developed distribution infrastructure for the alcohols, and their higher market cost.
A number of cities ran demonstration programs with ethanol or methanol buses in the 1990's: Minneapolis, Peoria, and Los Angeles ran ethanol buses, while New York City and Miami tested methanol buses. Dana Lowell of New York's MTA calls the agency's experiment with methanol "a total disaster," and compares it with the outcome of a similar program in Los Angeles. In the early 1990's, when New York ran the program, according to Lowell, methanol engines were prohibitively expensive, hard to get a hold of, and too difficult to maintain.
While evaluations of performance vary somewhat from one transit agency to another, (Peoria, for example cited no notable maintenance problems) those interviewed for this report agree that the cost of running buses on either alcohol fuel was a significant disincentive to continuing the program.
At the time of Peoria's program (1992-1998), ethanol cost 18¢ more than diesel on a per mile basis. At the time of Los Angeles' program (1989-1997), ethanol cost 35¢ more. Higher costs, in these cases, are incurred in the production process, and in the lower energy content of alcohol-based fuels, which results in higher total fuel consumption. Despite ethanol's greenhouse gas advantages, mechanical difficulties and high costs make it an unlikely resource in the effort to reduce vehicular emissions.
More...
Click here for links to AFV Funding Information.